Flannery's Pub Bartender Ellie Sanders can taste the difference in a perfectly poured Guinness. “It’s so beautiful,” she says. “You almost get a milk mustache from it.” Since the perfect pour must follow a Guinness-regulated process, we consulted with certified area pubs on what to look for in a proper pint.

1. Line Check
Guinness shouldn’t be hooked up to a standard carbon dioxide line, says Mullarkey’s Irish Pub owner John Bowers. Guinness requires a mixture of 75 percent nitrogen and 25 percent CO2. “That’s what gives you the creamy head,” he says.

2. Inspect Your Glass
“The properly poured pint should be in a beer-clean glass,” explains Harp bar manager Kim Arnold, meaning it’s been washed only with other glasses. Your glass is beer-clean if, as you drink it down, the head leaves rings around the sides.

3. Watch Your Pour
“[You] hold the glass under the tap at a 45-degree angle, filling it three-quarters of the way,” Sanders says. Some may say two-thirds, but ideally — if you’ve got an official glass — your first pour falls somewhere between the top and bottom of the harp.

4. Now … We Wait
Next, the glass should be set down to let the stout settle for two minutes, Arnold says. At Mullarkey’s, Bowers gives it upwards of three minutes to ensure it’s completely settled and to avoid the dreaded “bishops collar,” or a head that’s too big.

5. The Top-Off
“Once the cascading is done and the beer is completely dark, you take it back to the tap, straight up, and slow-pour the rest,” Sanders says. The head should be no more than an inch high, creating “a little mound, like a puffy cloud” over the rim, adds Arnold.